In general, acrylonitrile-butadiene-styrene resin (hereinafter, referred to as an ‘ABS resin’) has been widely used in electric/electronic products, automobile components, general goods, and the like, due to excellent impact resistance, mechanical strength, surface property, workability, and the like.
However, ABS resin includes a chemically unstable double bond in a rubber component in the resin, such that aging of the rubber component may easily occur upon exposure to ultraviolet rays. Since the ABS resin has poor weather resistance and light resistance, when a product made of the ABS resin is left outside for a long period of time, discoloration and deterioration of physical properties are relatively significantly increased over time, such that the ABS resin is not suitable for outdoor usage.
To overcome this problem, post-production processes such as plating or coating can be performed on a molded article manufactured of the ABS resin, or a large amount of a UV stabilizer can be added when extruding the ABS resin. However, the former case has disadvantages in that such processes can be complicated, and defect rates can be high. The latter case also has disadvantages such as increased manufacturing costs and unsatisfactory long term weather resistance.
In order to overcome such limitations of uses for ABS resin, various resins having excellent weather resistance have replaced ABS resin. For example, acrylate-styrene-acrylonitrile resin (hereinafter, referred to as an ‘ASA’ resin) has been widely used as a substitute for ABS resin in outdoor applications. ASA resin has excellent weather resistance, light resistance, chemical resistance, thermal resistance, and the like, and is appropriate for use in outdoor exterior materials that are exposed to sunlight, such as outdoor electric/electronic products, automobile exterior materials, building materials, and the like.
When used for automobile interior and exterior materials, optimal color mixing and excellent weather resistance for aesthetic appearance are required in black-based colors which are mainly used. In a related art, there has been research into technology for improving weather resistance by using an inorganic material having low reactivity, or improving colorability of a base resin, or adding an additive helping dispersion of pigments. However, using a large amount of inorganic pigments or additives can decrease mechanical properties of the resin, such as impact strength, and the like.
Korean Patent Laid-Open Publication No. 10-2013-0075812 discloses an ASA resin composition containing an acrylic graft copolymer; two different kinds of vinyl cyanide-aromatic vinyl copolymers, each having different weight average molecular weight; and an alpha methyl styrene-based terpolymer. However, in this case, there are still problems in that pigment colorability can be decreased and weather resistance may not be sufficiently improved.